In the field of electrical engineering, a partial discharge (PD) is a localized dielectric breakdown of a portion of a solid or fluid electrical insulation system subjected to a high voltage stress. When the electrical insulation system breaks down, electrical discharges are emitted in a tree like pattern within the insulation, commonly referred to as an electrical tree. Electrical treeing in dielectric insulation is a damaging process due to the partial discharge and to the progression of the partial discharge throughout the stressed dielectric insulation. Once initiated, partial discharge (PD) causes progressive deterioration of the insulating material, ultimately leading to electrical breakdown of the system. The effects of partial discharge within high voltage cables and equipment, if not detected and corrected, can ultimately leading to complete failure of the system. As such, partial discharge prevention and detection are essential to ensure reliable, long-term operation of high voltage equipment.
By measuring the partial discharge occurring within the dielectric insulation, the overall dielectric condition of high voltage equipment can be evaluated and electrical treeing in the insulation can be detected and located. The use of partial discharge measurement systems is especially important for shipboard power systems, and particularly for all-electric ships, where partial discharge within the dielectric insulation is presumed to be a major source of degradation of the system as a result of the unique operating circumstances generally experienced onboard a ship.
Various partial discharge detection and measurement methods are known in the art. The methods and devices currently known in the art monitor the partial discharge associated with insulation of electrical machines and provide warning signals when the partial discharge activity within the insulation exceeds a predetermined threshold. However, the current state of the art devices are only capable of monitoring the current condition of the machine insulation and are incapable of determining the remaining useful life of the machine insulation system.
Accordingly, what is needed is a more accurate and more complete electrical tree simulation model coupled with a method for determining the extent of damage and remaining life of a machine insulation system. However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the field of this invention how the shortcomings of the prior art could be overcome.
All referenced publications are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.
While certain aspects of conventional technologies have been discussed to facilitate disclosure of the invention, Applicants in no way disclaim these technical aspects, and it is contemplated that the claimed invention may encompass one or more of the conventional technical aspects discussed herein.
The present invention may address one or more of the problems and deficiencies of the prior art discussed above. However, it is contemplated that the invention may prove useful in addressing other problems and deficiencies in a number of technical areas. Therefore, the claimed invention should not necessarily be construed as limited to addressing any of the particular problems or deficiencies discussed herein.
In this specification, where a document, act or item of knowledge is referred to or discussed, this reference or discussion is not an admission that the document, act or item of knowledge or any combination thereof was at the priority date, publicly available, known to the public, part of common general knowledge, or otherwise constitutes prior art under the applicable statutory provisions; or is known to be relevant to an attempt to solve any problem with which this specification is concerned.